Frame structure for supporting a surface mount device light emitting diode used as a side light source

ABSTRACT

A frame structure includes a first metallic frame, a second metallic frame, and a plastic housing. The first metallic frame has extension portions extending outwardly, and the first metallic frame is separately positioned from the second metallic frame. The first metallic frame and the second metallic frame respectively have different electrical polarities. The plastic housing is connected with the first metallic frame and the second metallic frame, and the plastic housing and the two extension portions form a receiving space so the two extension portions are positioned at two ends of the plastic housing. The plastic housing receives the LED die and a packaging layer. The extension portions expose out of the plastic housing or are nestled within the plastic housing. The frame structure has a good efficiency of heat dissipation because the metal is not transparent and efficiency of heat dissipation is high without light leakage.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a frame structure for supporting alight emitting diode, and in particular to a frame structure forsupporting a surface mount device (SMD) light emitting diode used as aside light source.

2. Description of Related Art

Light emitting diode (LED) is a semiconductor device that emits lightwhen electrically biased in the forward direction. When voltage isapplied to the semiconductor device such as gallium phosphide (GaP) orgallium arsenide (GaAs), charge-carriers (electrons and electron holes)flow into the junction from electrodes because of voltage. Whenelectrons meet electron holes, the semiconductor device releases energyin the form of a photon unlike incandescent and discharging lightsources. Because the LED is an electroluminescent device, lifeexpectancy of the LED is up to 100,000 hours. Besides, the LED iscompact, energy-saving, fit to mass production and clean so the LED iswidely used, such as traffic lights and signals, backlight forelectronic appliance, car's break light and lighting apparatus etc.

Referring to FIGS. 1 and 2, they show a frame structure for a surfacemount device (SMD) LED used as a side light source. The frame structureis used to support a LED die so that a LED structure is formed and usedas side-type backlight module for cellular phones or personal digitalassistants (PDAs). The frame structure includes a plastic housing 10 aand two metallic support frames 20 a with different electricalpolarities. The plastic housing 10 a includes a receiving space 11 a,and the two metallic support frames 20 a are positioned within theplastic housing 10 a. A LED die 30 a is positioned at one of the twometallic support frames 20 a, and the LED die 30 a and the two metallicsupport frames 20 a are electrically connected by conductive wires (notshown). The LED die 30 a is packaged by an epoxy layer or a siliconlayer and a packaging layer 40 a, and the packaging layer 40 a includesa variety of fluorescent powder. Besides, positive and negativepolarities of electrical current are respectively applied to the twometallic support frames 20 a so that the LED die 30 a emits light.

However, electronic appliances need to be slim, compact andlight-weighted to meet users' requirement. Thus, the frame structure fora surface mount device (SNM) LED should be smaller and thinner. If theplastic housing 10 a is too smaller, then thickness d is thin so thatthe LED die 30 a emits light through the plastic housing 10 a. That iswhat is so called “light leakage”. Besides, the two metallic supportframes 20 a are mostly enclosed by the plastic housing 10 a so it is noteasy for the LED die 30 a to dissipate heat. Life expectancy of the LEDdie 30 a is significantly shortened because of high temperature.

Thus, there is a need for a frame structure for supporting a lightemitting diode used as a side light source.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a frame structurefor supporting a surface mount device (SMD) light emitting diode used asa side light source. The frame structure has metallic frame includingextension portions which are positioned besides the plastic housing.Because the metal is not transparent and its efficiency of heatdissipation is high, the frame structure has a good efficiency of heatdissipation without light leakage.

To achieve the object of the frame structure for supporting a surfacemount device (SMD) light emitting diode used as a side light source, itincludes at least one first metallic frame, at least one second metallicframe, and a plastic housing. The first metallic frame has two extensionportions extending outwardly from its two ends, and the first metallicframe is in vicinity of and separated from the second metallic frame.The first metallic frame and the second metallic frame respectively havedifferent electrical polarities. The plastic housing is connected withthe first metallic frame and the second metallic frame, and the plastichousing and the two extension portions form a receiving space so thatthe two extension portions are positioned at two ends of the plastichousing.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention can be fully understood from the followingdetailed description and preferred embodiment with reference to theaccompanying drawings, in which:

FIG. 1 is a perspective view of a frame structure for a surface mountdevice (SMD) LED used as a side light source in prior art;

FIG. 2 is a cross-section of a frame structure for a surface mountdevice (SMD) LED used as a side light source in prior art;

FIG. 3 is a perspective view of the first embodiment of the presentinvention;

FIG. 4 is an exploded view of a first metallic frame and a secondmetallic frame according to the first embodiment of the presentinvention;

FIG. 5 is a perspective view of a first metallic frame and a secondmetallic frame according to the first embodiment of the presentinvention;

FIG. 6 is a cross-section of a first embodiment of the presentinvention;

FIG. 7 is a perspective view of the second embodiment of the presentinvention;

FIG. 8 is a perspective view of a first metallic frame and a secondmetallic frame according to the second embodiment of the presentinvention;

FIG. 9 is an exploded view of a first metallic frame and a secondmetallic frame according to the second embodiment of the presentinvention;

FIG. 10 is a view illustrating how the present invention is implemented;and

FIG. 11 is another view illustrating how the present invention isimplemented.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following detailed description is of the best presently contemplatedmodes of carrying out the invention. This description is not to be takenin a limiting sense, but is made merely for the purpose of illustratinggeneral principles of embodiments of the invention. The scope of theinvention is best defined by the appended claims.

Referring to FIG. 3, it illustrates a frame structure for supporting asurface mount device (SMD) light emitting diode used as a side lightsource including at least one first metallic frame 10, at least onesecond metallic frame 20 and a plastic housing 30.

FIGS. 3-6 illustrate the first embodiment of the present invention. Forsimplicity, there is one first metallic frame 10 and one second metallicframe 20 shown in FIGS. 3-6. Number of the first metallic frame 10 andone second metallic frame 20 is not limited to one. The first metallicframe 10 and the second metallic frame 20 are U-shaped and made ofmetallic material with good conductivity. Besides, the first metallicframe 10 and the second metallic frame 20 have different electricalpolarities (positive polarity and negative polarity). The first metallicframe 10 and the second metallic frame 20 have base portions 11 and 21respectively. Two extension portions 12 horizontally extend from twoends of the base portion 11 of the first metallic frame 10, and twoextension portions 22 horizontally extend from two ends of the baseportion 21 of the first metallic frame 20.

However, number of the first metallic frame 10 and the second metallicframe 20 may be 2 (not shown in the figure). That is, there are two setsof the base portion 11 and 21, and the extension portions 12 and 22horizontally extend from each of two sets of the base portion 11 and 21.

The plastic housing 30 is manufactured by injection molding process toconnect the first metallic frame 10 and the second metallic frame 20 sothat the first metallic frame 10 and the second metallic frame 20 areseparately positioned. Besides, the plastic housing 30 and the extensionportions 12 and 22 form a receiving space 31 so that the extensionportions 12 and 22 are respectively positioned at the top surface andbottom surface near the sides of the plastic housing 30. The baseportions 11 and 21 are connected with the plastic housing 30 so outersurface of the base portions 11 and 21 expose out of the plastic housing30, and the base portions 11 and 21 and the plastic housing 30 are inthe same plane. Besides, the plastic housing 30 encloses the extensionportions 12 and 22; that is, the extension portions 12 and 22 arepositioned within the plastic housing 30 (not shown). Alternately, oneof the extension portions 12 and 22 exposes out of the outer surface ofthe plastic housing 30, and the other one of the extension portions 12and 22 is positioned within the plastic housing 30. Meanwhile, theplastic housing 30 fills a gap between the first metallic frame 10 andthe second metallic frame 20 so that a separation strip 32 is formed toseparate electrical polarities of the first metallic frame 10 and thesecond metallic frame 20.

According to the present invention, the plastic housing is made ofnon-conductive polymer material such as Polyphthalamide (PPA),Polybutylene Terephthalte (PBT), Polycarbonate (PC), PolymethylMethacrylate (PMMA) or other thermo-plastic resin etc.

Referring to FIG. 5, the extension portions 12 and 22 of one of thefirst metallic frame 10 and the second metallic frame 20 further extendinwardly so protrusions 13 and 23 are formed and positioned within theplastic housing 30 or positioned at two sidewalls of the receiving space31. As shown in FIGS. 4-6, rough surface portions 14 and 24 or holes 15and 25 are formed at the base portions 11 and 21 of the first metallicframe 10 and the second metallic frame 20 so as to secure the plastichousing 30. Besides, the protrusions 13 and 23 further include the holes15 and 25 to secure the plastic housing 30. Alternately, the roughsurface portions 14 and 24 may be in form of grooves or equivalents. Thefirst metallic frame 10 and the second metallic frame 20 further includemetallic reflective layers (not shown) respectively, and the metallicreflective layers are made of metal with high reflectivity such assilver by electroplating to improve reflectivity of light.

Referring to FIGS. 7-9, the second embodiment of the present inventionis unlike the first embodiment. The extension portions 12 of the firstmetallic frame 10 further extend toward the base portion 21 of thesecond metallic frame 20 for a certain length so that the extensionportion 12 is positioned out of the second metallic frame 20. Besides,the extension portions 12 expose out of the surface of the plastichousing 30, and the extension portions 12 are in same plane with theplastic housing 30. That is, the second metallic frame 20 just has thebase portion 21. Bended portions 16 and 26 respectively extend away fromthe ends of the base portions 11 and 21 of the first metallic frame 10and the second metallic frame 20, and the bended portions 16 and 26expose out of and are in contact with the plastic housing 30. The roughsurface portions 14 and 24 are formed at the base portions 11 of thefirst metallic frame 10, and the bended portion 26 of the secondmetallic frame 20 is positioned within the plastic housing 30. The baseportions 11 and 21 of the first metallic frame 10 and the secondmetallic frame 20 have the holes 15 and 24 to improve rigidity of theplastic housing 30.

Two protrusions 13 extend inwardly and are bended from the sides of theextension portion 12 respectively, and the two protrusions 13 areinterleaved and positioned within the two sides of the plastic housing30 to improve rigidity of the first metallic frame 10 and the plastichousing 30.

Referring to FIGS. 6 and 10, a LED die (or LED chip) 40 are positionedat the base portion 11 of the first metallic frame 10 or positioned atthe base portion 21 of the second metallic frame 20. Then, the LED die40 is electrically connected with the base portions 11 and 21 of thefirst metallic frame 10 and the second metallic frame 20 respectively bytwo conductive wires 41. A transparent packaging layer 50 is attached tothe inner surface of the receiving space 31 so as to enclose the LED die40. The transparent packaging layer 50 may be made of but not limited toepoxy resin, silicone or other thermoplastic resin etc. Besides, theepoxy resin, silicone or other thermoplastic resin may be mixed withflorescent powders (such as yellow phosphor) so as to improve luminanceof the LED die 40. When the first metallic frame 10 and the secondmetallic frame 20 are electrically connected with a printed circuitboard 60 by the extension portions 12 and 22 or the bended portions 16and 26, current flows through the first metallic frame 10 and the secondmetallic frame 20 by two conductive wires 41 so that the LED die 40emits light beams.

Referring to FIGS. 10 and 11, the frame structure for surface mountdevice (SMD) LED of the present invention is used to prevent the lightbeams from penetrating through the plastic housing 30 and has a highefficiency of heat dissipation. The extension portions 12 and 22 of thefirst metallic frame 10 and the second metallic frame 20 expose out ofthe plastic housing 30, and the LED die 40 emits light beams toward thesame direction and intensity of light beams is improved because metal isnot transparent. The light beams will not penetrate through the plastichousing 30 and “light leakage” will not occur when the LED die 40 isthin and compact. Besides, when the LED die 40 is powered on, heat isgenerated and efficiently dissipated through the first metallic frame 10or the second metallic frame 20 because of high efficiency of metal'sheat dissipation. It prevents the LED die 40 from failure or lifeexpectancy is shortened because of worse heat dissipation or hightemperature of the plastic housing 30.

Advantages of the present invention can be summarized as in thefollowing:

1. According to the first embodiment and the second embodiment of thepresent invention, the extension portions 12 and 22 of the firstmetallic frame 10 or the second metallic frame 20 expose out of theplastic housing 30 or are positioned within the plastic housing 30, andthe first metallic frame 10 of the second embodiment further extendstoward the second metallic frame 20 so that the first metallic frame 10exposes out of or is positioned within the plastic housing 30.Furthermore, by utilizing metal is not transparent and has high heatconductivity, “light leakage” will not occur and heat can be efficientlydissipated.

2. The rough surface portions 14 and 24 or holes 15 and 25 are formed atthe first metallic frame 10 and the second metallic frame 20 to improvethe rigidity of the plastic housing 30, the first metallic frame 10 andthe second metallic frame 20.

3. The protrusions 13 and 23 of the present invention are positionedwithin the plastic housing 30 to improve adhesion of the plastic housing30 to the first metallic frame 10 and the second metallic frame 20.

4. A metallic conductive layer is attached to inner surfaces of thefirst metallic frame and the second metallic frame of the presentinvention to improve reflectivity of the LED die 40.

While the invention has been described with reference to the preferredembodiments, the description is not intended to be construed in alimiting sense. It is therefore contemplated that the appended claimswill cover any such modifications or embodiments as may fall within thescope of the invention defined by the following claims and theirequivalents.

1. A frame structure for supporting a surface mount device (SMD) lightemitting diode used as a side light source, comprising: at least onefirst metallic frame, having two extension portions extending outwardlyfrom its two ends; at least one second metallic frame, in vicinity ofand separated from the second metallic frame, and the first metallicframe and the second metallic frame respectively having differentelectrical polarities; and a plastic housing, connected with the firstmetallic frame and the second metallic frame, and the plastic housingand the two extension portions forming a receiving space so that the twoextension portions are positioned at two ends.
 2. The frame structurefor supporting a surface mount device (SMD) light emitting diode used asa side light source as claimed in claim 1, wherein a metal reflectivelayer is applied to inner surfaces of the first metallic frame and thesecond metallic frame.
 3. The frame structure for supporting a surfacemount device (SMD) light emitting diode used as a side light source asclaimed in claim 1, wherein the first metallic frame and the secondmetallic frame respectively have rough surface portions so as to securethe plastic housing.
 4. The frame structure for supporting a surfacemount device (SMD) light emitting diode used as a side light source asclaimed in claim 1, wherein the first metallic frame and the secondmetallic frame respectively have holes so as to secure the plastichousing.
 5. The frame structure for supporting a surface mount device(SMD) light emitting diode used as a side light source as claimed inclaim 1, wherein bended portions extend away from one ends of the firstmetallic frame and the second metallic frame, and the bended portionsexpose out of two sides of the plastic housing.
 6. The frame structurefor supporting a surface mount device (SMD) light emitting diode used asa side light source as claimed in claim 5, wherein the rough surfaceportions are positioned in which the plastic housing and the bendedportions are assembled.
 7. The frame structure for supporting a surfacemount device (SMD) light emitting diode used as a side light source asclaimed in claim 1, wherein a light emitting diode die is electricallyconnected with the first metallic frame and the second metallic framerespectively by two conductive wires, and a transparent packaging layerattached to inner surface of the receiving space so as to enclose thelight emitting diode die.
 8. The frame structure for supporting asurface mount device (SMD) light emitting diode used as a side lightsource as claimed in claim 7, wherein the transparent packaging layer ismade of epoxy resin or silicone, and the packaging layer includes avariety of fluorescent paint to improve luminance.
 9. The framestructure for supporting a surface mount device (SMD) light emittingdiode used as a side light source as claimed in claim 1, wherein theextension portions expose out of the plastic housing or are nestledwithin the plastic housing.
 10. The frame structure for supporting asurface mount device (SMD) light emitting diode used as a side lightsource as claimed in claim 1, wherein protrusions extend inwardly fromone end of the extension portions and positioned within the plastichousing or the receiving space.
 11. The frame structure for supporting asurface mount device (SMD) light emitting diode used as a side lightsource as claimed in claim 1, wherein the extension portions furtherextend toward the second metallic frame so that the extension portionsare positioned outside of the second metallic frame.
 12. The framestructure for supporting a surface mount device (SND) light emittingdiode used as a side light source as claimed in claim 1, wherein asecond extension portion extends outwardly from the second metallicframe and are positioned two sides of the plastic housing so that thesecond metallic frame and the plastic housing form the receiving space.13. The frame structure for supporting a surface mount device (SMD)light emitting diode used as a side light source as claimed in claim 12,wherein the extension portion of the second metallic frame exposes outof the plastic housing or are nestled within the plastic housing. 14.The frame structure for supporting a surface mount device (SMD) lightemitting diode used as a side light source as claimed in claim 12,wherein a protrusion extends inwardly from one side of the extensionportion of the second metallic frame and positioned within the plastichousing or within the receiving space.
 15. The frame structure forsupporting a surface mount device (SMD) light emitting diode used as aside light source as claimed in claim 1, wherein the plastic housing ismade of non-conductive polymer material.
 16. The frame structure forsupporting a surface mount device (SMD) light emitting diode used as aside light source as claimed in claim 1, wherein the plastic housingfills a gap between the first metallic frame and the second metallicframe so that a separation strip is formed to separate electricalpolarities of the first metallic frame and the second metallic frame.17. A metallic frame of a frame structure for supporting a surface mountdevice (SMD) light emitting diode used as a side light source,comprising: a base portion; and two extension portions, extending fromtwo ends of the base portion.
 18. The frame structure for supporting asurface mount device (SMD) light emitting diode used as a side lightsource as claimed in claim 17, wherein the base portion has roughsurface portions.
 19. The frame structure for supporting a surface mountdevice (SMD) light emitting diode used as a side light source as claimedin claim 17, wherein the base portion has holes.
 20. The frame structurefor supporting a surface mount device (SMD) light emitting diode used asa side light source as claimed in claim 17, wherein a bended portionextends away from one end of the base portion.
 21. The frame structurefor supporting a surface mount device (SMD) light emitting diode used asa side light source as claimed in claim 20, wherein the bended portionhas a rough surface portion.
 22. The frame structure for supporting asurface mount device (SMD) light emitting diode used as a side lightsource as claimed in claim 17, wherein a protrusion extends from oneside of the extension portion.